From 5447eca29c66d2283f536b8b0c3b94c5a73a8801 Mon Sep 17 00:00:00 2001
From: acevest <zhaoyanbai@126.com>
Date: Tue, 24 Sep 2024 23:25:13 +0800
Subject: [PATCH] =?utf8?q?default=20tty=E6=9C=80=E9=A1=B6=E4=B8=8A?=
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---
 kernel/setup.c | 11 ++++++++++-
 kernel/tty.c   | 10 ++++++----
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/kernel/setup.c b/kernel/setup.c
index 6bf2142..adffa9d 100644
--- a/kernel/setup.c
+++ b/kernel/setup.c
@@ -45,6 +45,15 @@ const char *version = "KERNEL v" VERSION " @" BUILDER
                       "]"
                       "\n\n";
 
+void print_kernel_version() {
+    //
+    extern tty_t *const default_tty;
+    tty_write_at(default_tty, 0, 0, version, (size_t)strlen(version));
+
+    //
+    printk(version);
+}
+
 void setup_kernel() {
     printk("sysenter esp mode: %s\n",
 #if FIXED_SYSENTER_ESP_MODE
@@ -87,7 +96,7 @@ void setup_kernel() {
     detect_cpu();
     boot_delay(DEFAULT_BOOT_DELAY_TICKS);
 
-    printk(version);
+    print_kernel_version();
     boot_delay(DEFAULT_BOOT_DELAY_TICKS);
 
     extern tty_t *const monitor_tty;
diff --git a/kernel/tty.c b/kernel/tty.c
index f574aeb..370c2f9 100644
--- a/kernel/tty.c
+++ b/kernel/tty.c
@@ -129,9 +129,11 @@ void tty_do_scroll_up(tty_t *tty) {
         return;
     }
 
-    //
-    char *dst = (char *)tty->base_addr;
-    for (int src = BYTES_PER_LINE; src < (MAX_Y * BYTES_PER_LINE); src++) {
+    // 如果是default_tty则保留用来显示内核版本及编译时间信息
+    const int keep = tty != default_tty ? 0 : BYTES_PER_LINE;
+
+    char *dst = (char *)tty->base_addr + keep;
+    for (int src = BYTES_PER_LINE + keep; src < (MAX_Y * BYTES_PER_LINE); src++) {
         *dst++ = *(char *)(tty->base_addr + src);
     }
 
@@ -260,7 +262,7 @@ void tty_switch(tty_t *tty) {
     outb(VGA_CRTC_START_ADDR_H, VGA_CRTC_ADDR);
     outb((offset >> 8) & 0xFF, VGA_CRTC_DATA);
     outb(VGA_CRTC_START_ADDR_L, VGA_CRTC_ADDR);
-    outb((offset)&0xFF, VGA_CRTC_DATA);
+    outb((offset) & 0xFF, VGA_CRTC_DATA);
     irq_restore(flags);
 
     current_tty = tty;
-- 
2.44.0